lib / string_helpers: introduce string_escape_mem()

This is almost the opposite function to string_unescape().  Nevertheless
it handles \0 and could be used for any byte buffer.

The documentation is supplied together with the function prototype.

The test cases covers most of the scenarios and would be expanded later
on.

[[email protected]: avoid 1k stack consumption]
Signed-off-by: Andy Shevchenko <[email protected]>
Cc: "John W . Linville" <[email protected]>
Cc: Johannes Berg <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: Joe Perches <[email protected]>
Cc: Wu Fengguang <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

1 files changed, 31 insertions, 0 deletions

diff --git a/include/linux/string_helpers.h b/include/linux/string_helpers.h
index 5a30f2a86239..6eb567ac56bc 100644
--- a/include/linux/string_helpers.h
+++ b/include/linux/string_helpers.h
@@ -37,4 +37,35 @@ static inline int string_unescape_any_inplace(char *buf)
 	return string_unescape_any(buf, buf, 0);
 }
 
+#define ESCAPE_SPACE		0x01
+#define ESCAPE_SPECIAL		0x02
+#define ESCAPE_NULL		0x04
+#define ESCAPE_OCTAL		0x08
+#define ESCAPE_ANY		\
+	(ESCAPE_SPACE | ESCAPE_OCTAL | ESCAPE_SPECIAL | ESCAPE_NULL)
+#define ESCAPE_NP		0x10
+#define ESCAPE_ANY_NP		(ESCAPE_ANY | ESCAPE_NP)
+#define ESCAPE_HEX		0x20
+
+int string_escape_mem(const char *src, size_t isz, char **dst, size_t osz,
+		unsigned int flags, const char *esc);
+
+static inline int string_escape_mem_any_np(const char *src, size_t isz,
+		char **dst, size_t osz, const char *esc)
+{
+	return string_escape_mem(src, isz, dst, osz, ESCAPE_ANY_NP, esc);
+}
+
+static inline int string_escape_str(const char *src, char **dst, size_t sz,
+		unsigned int flags, const char *esc)
+{
+	return string_escape_mem(src, strlen(src), dst, sz, flags, esc);
+}
+
+static inline int string_escape_str_any_np(const char *src, char **dst,
+		size_t sz, const char *esc)
+{
+	return string_escape_str(src, dst, sz, ESCAPE_ANY_NP, esc);
+}
+
 #endif